Shell mold making machine



June 4, 1957 cs. L. BACHNER SHELL MOLD MAKING MACHINE 5 Sheets-Sheet 1 Filed March 17, 1953 9 5 5 3 D 7 7. 7 m 3 A 4, a,

a "m w .5 Hg a HH m. M w a w a 41:1 2 2. 3... 4 m .4 A w June 4, 1957 G. BACHNER SHELL MOLD MAKING mourns 5 Sheets-Sheet 2 Filed llaroh'lw, 1953 required and also when pairs of such mating such molds together United States Patent to Bachner Valyi Development Heights, 111., a corporation of George Louis Bachner,

by mesne assignments, Corporation, Arlington Delaware Application March 17, 1953, Serial No. 342,887 19 Claims. (Cl. 22--20) This invention relates to a mold making machine, and

more particularly to a machine for making shell molds from pulverulent mixes of sand and a resin. In the making of shell molds, a mixture of a fusible resin and sand, or other suitable aggregate, is brought into contact with a heated pattern and contact continued therebetween until a relatively thin layer of the sandresin mix adjacent the heated surface of the pattern has become sufficiently fused to render the layer coherent. Thereafter, the excess of the loose sand-resin mix is removed, as by inverting the die, and the partially fused layer further heated in an oven to cure the resin.

Pairs of shell molds so prepared are used in the casting of metal and alloys to obtain precision castings that require a minimum of finishing operations. In the casting as heretofore carried out, pairs of shell molds were clipped together at their peripheries and backed by metal shot to reinforce the backs of the shell molds and prevent them from buckling during the pouring of the molten metal into the mold, prior to its solidification. This previous method has had the disadvantage of being rela tively laborious and expensive due to the amount of labor the necessity of applying metal shot, or the like, for the backing of shell molds during the pouring operation, particularly where relatively large castings are being poured.

In addition to developing an improved and simplified method of making shell molds that eliminates the neces sity of the use of metal shot, or other loose backing material for the molds during the pouring operation, I have also devised a machine that is capable of carrying out automatically the various steps of my method. Shell molds made automatically on a machine of my present invention are generally similar to the shell molds heretofore known, but differ from the conventional shell molds in providing what are here termed as pressure points, or pressure distr'buting surfaces, whereby pairs of mating shell molds may be placed in back-to-back, clampedtogether relationship for receiving the poured metal.

Such pressure points are provided by so arranging and constructing the die used in forming the shell molds that there are formed in the resulting shell mold a plurality of surfaces, usually more or less symmetrically spaced, on the back of the mold, which surfaces are substantially coplanar and provide areas of contact with similar pressure points on the next adjacent shell mold shell molds are clamped together by applying endwise clamping pressure through the contacting pairs of mating shell molds. These pressure points serve to rigidity the shell molds, the back walls of which are not otherwise sufliciently rigid and strong to accommodate, without likelihood of rupturing, the amount of pressure necessary to hold a plurality of during the pouring operation without the liability of possible separation of the mating surfaces of associated mold halves. By the use of such pressure points, the pressure applied during the clamping 2,794,222 Patented June 4, 1957 of a plurality of pairs of shell molds and the pressure developed hydrostatically by the poured metal, are relatively uniformly distributed over the back walls of the mold halves through the material of the mold as to their mating faces. Such distribution and equalization of compressive forces enables the thin shells to stand up without danger of rupturing or collapsing, whereas if there were no such pressure points, localized pressures would build up during the clamping and pouring operations that would be in excess of what the compressive and tensile strength of the shells could withstand.

The machine of my present invention is particularly adapted for making shell mold halves having pressure points, or pressure distributing surfaces, of the type and for the purpose just described. The machine includes an invertible frame on which are mounted a heated die and a hopper for containing a sand-resin mix, the die and hopper being relatively movable into and out of cooperative association and the hopper being provided with a gate valve for controlling the release of the sand-resin mix onto the die when the frame is in its normal, upright position, and for admitting the return of an excess of the sand-resin mix from the face of the die when the frame is in its inverted position. Means are provided for heating the die so that when the pulverulent sand-resin mix is dumped thereon from the hopper, a thin layer of the mix will quickly fuse to the extent necessary to from a coherent layer conforming to and in adherent contact with the patterns on the face of the die. It is only the excess of loose, pulverulent sand-resin mix that is dumped back into the hopper when the die and hopper are inverted.

My machine also includes an oven that is movable into place over the face of the die to complete the cure of the sand-resin layer formed thereon. As one mode of best carrying out the formation of pressure points, the oven carries at its leading end and transversely of its open bottom, a scraper bar which serves to scrape off any excess of the sand-resin mix down to a predetermined level, which is conveniently determined by the height of opposed side walls defining the pattern-bearing face of the die. Thus, as the oven moves into place, the scraper bar is caused to move along with the oven and in contact with the opposed side walls of the die to remove any excess of the loose resin-mix and provide the coplanar pressure points, or areas, previously described. After the curing step has been effected, the oven is withdrawn and the finished mold half is then ready for stripping from the die for subsequent use or storage.

It is an object of this invention to provide a novel and improved construction of a machine for making shell molds and the like, wherein the several parts of the machine for performing the various shell mold forming steps are so constructed, arranged and correlated that the entire operation is substantially automatic.

It is a further important object of this invention to provide a machine that includes the various mechanisms necessary for the making of sand-resin shell molds of an improved construction, such that a plurality of the molds can be assembled and clamped together in back-to-back relationship for the pouring operation without the necessity of backing up the molds with metal shot, or other loose backing material.

It is a further important object of this invention to provide a shell mold making machine that includes a heated die for forming thereon a partially fused layer of a sand-resin mix, an oven movable intocooperation with the die for completing the curing of said layer while the same is in adhering contact with the patterns carried by the die, and a scraper bar carried by the oven and ef- Z fective as the oven is moved into place over the die to level ofi the back surfaces of said sand-resin layer to provide pressure distributing areas in the finished mold half.

It is a further importantv object of this invention to provide a shell mold making machine that. has relatively movable parts for carrying out the various steps of making a shell mold of my improved construction, and that has electrically operated controls for automatically effecting the movements of such parts in properly timed relationship.

Other and further important objects of this invention will become apparent from the following description and appended claims.

On the drawings:

Figure l is a side elevational view of a machine embodying the principles of my invention, with parts broken away and parts dotted in to illustrate the operation.

Figure 2 is an end elevational view of the machine.

Figure 3 is a diagrammatic e'nd elevational view, otherwise similar to Figure 2 but showing the invertible frame work carrying the die and hopper in its normal, upright position, with the hopper and die in cooperative closed relationship for the gravity dumping of sand-resin mix from the' hopper on to the face of the die.

Figure 4 is a diagrammatic end elevational view similar to that of Figure 3 but with the frame carrying the hopper and die in its inverted position, with the die above the hopper for returning an excess of the sand-resin mix from the surface of the die back into the hopper.

Figure 5 is an enlarged, broken, elevational detail view of mechanism for holding the invertible frame in its normal, upright position.

Figure 6 is an enlarged, fragmentary, detail view with parts in section taken substantially along the line VI-VI of Figure 2.

Figure 7 is an enlarged, fragmentary, detail view of the gate valve for the hopper, indicating in dotted lines the movement of the valve and end flap associated therewith.

Figure 8 is a fragmentary sectional view taken substantially along the line VIII--VIII of Figure 7.

Figure 9 is a top plan view of the face of a die illustrating the patterns and associated raised portions that are employed for the purpose of forming pressure points on the sand-resin shell molds made on my machine.

Figure 10 is a broken sectional view taken substantialand raised portions thereon, after the'excess of loose sandresin mix has been removed but before the scraping operation to provide coplanar pressure points, or' surfaces.

Figure 11 is a fragmentary sectional view, identical with Figure 10 except illustrating the scraper bar during the operation of scraping off the excess of sand-resin mix in the formation of pressure points, or surfaces, as: just referred to.

Figure 12 is a fragmentary, with parts in section, illustrating operative relationship to effect resin layer shown in Figure 11.

Figure 13 is a top plan view of on the die and with the lustrated in Figure 9.

Figure 14 is a fragmentary top plan view of a plurality of mated shell mold halves as they would be if clamped together for pouring, with portions broken away and in section to illustrate the Contact between pressure points, or pressure surfaces, formed on the backs of the molds.

Figure 15 is a fragmentary, detail top plan view of the oven, illustrating the electrical actuating and control means associated therewith.

Figure 16 is a wiring diagram for the automatic operadetail elevational view, the oven and die in cothe curing of the sanda shell mold half made patterns and raised portions il- 4 tion of the machine and its various movable parts in properly timed sequence.

As shown on the drawings:

The reference numeral 20 indicates generally the machine of my invention that is illustrated in Figures 1 and 2. Said machine 20 includes a stationary frame, or bed 21, which is made up of trapezoidal side frames 21a and 21b arranged in spaced parallel planes and braced by means of a lower cross piece 22. A platform 23 for supporting the driving means extends between the side frames 21a and 215 (Fig. l). Lengthwise extending bracing members 24 and 25 are also provided. Said stationary frame, or bed 21, also includes a side frame, indicated generally by the reference numeral 26 (Fig. 1), that is built out from the trapezoidal side frame 21b. Said side frame 26 includes upper horizontal side frame members 27 which are welded, or otherwise secured, to the longitudinal cross bar 24, with which said upper frame members 27 provide a supporting platform for an oven 30.

The stationary frame 21 serves to support an invertible frame, that is indicated generally by the reference numeral 31, and that is supported upon stub shafts 32 and 33 journaled in bearings 34 and 35, which, in turn, are mounted on the upper edges of the end frames 21a and 21b. The frame 31 is mounted from the stub shafts 32 and 33 by means of X-shaped members 36 and 37, secured to discs 38 and 39 carried by the inner ends ofsaid stub shafts 32 and 33, respectively. Said X-shaped members are provided adjacent the ends of their respective legs with supporting brackets 40, of which two are in vertical alignment when the frame 31 is in its normal, upright position, for supporting a cylindrical guide bar There are four such pairs of aligned brackets 40 and four such cylindrical guide bars 41 supported by respective sets of said brackets. Each of the guide posts 41 is provided with threaded ends 42 for receiving nuts 43. A platform 45 is secured by said nuts 43 on the threaded ends 42 of the four guide posts, at what would normally be the upper end of the frame 31. A pneumatic cylinder 46 for moving a hopper 47 is secured upon the platform 45 and is connected to said hopper 47 by a piston rod 48. Another cross platform, indicated by the reference numeral 50, is secured to the other ends of the guide bars 41 by means of similar nuts 43.

The hopper 47 comprises an elongated box of rectangular cross section that is supported at its ends for sliding movement on the guide bars 41 by means of contact shoes 51 that have segmental cylindrical surfaces bearing against the diametrically opposed inner surfaces of said guide bars. The hopper 47 is thus movable along the guide bars 41 in accordance with the actuation of the pneumatic cylinder 46 and the connecting rod 48. The lower end of the hopper 47 is open and is defined by an end flange 55, which is of such dimensions as to fit snugly against the open end of a die, indicated generally by the reference numeral 56 (Figs. 1, 2, 3, 4 and 12). Said die 56 is suitably supported from the lower cross platform 50.

The hopper 47 is provided with a gate valve 60, which is best shown in F'gure 6. Said gate valve 60 is consaid hopper 47 to provide a mounting for said pneumatic cylinder 62', the outer end of which is further supported by means of a strap 64 (Fig. 1) connected at its upper end to the upper end 65 of said hopper 47. Said frame 63 includes guideways for the side edges of the gate valve 60 as it moves from open to closed position. Said guideways comprise upper and lower angle irons (Fig. 8) 65 and 66, respectively, a spacing bar 67 between the outwardly extending horizontal flanges, and bolts 68 passing through said flanges and spacing bar and securing the same together. The gate valve 60 extends into the guideways 70 so formed, which, it will be noted- (Fig. 7), extend along both sides and the full width of the hopper 47.- The length of travel of the gate valve is such that the rear side of the hopper 47, as at 71, is slotted to permit the rear edge 72 of the gate valve to extend therethrough at the extremity of its closing travel. A spring urged flap 73 normally closes the slot except when it is forced into the open position illustrated in dotted lines (Fig. 7) by the gave valve 60. The purpose of extending the limit of travel of the gate valve 60, as just described, is to enable the gate valve to fully close off the interior of the hopper and also to prevept packing of the contents of the hopper between the end edge of the gate valve and the rear wall of the hopper.

The hopper 47 is itself fed from a supply of the moldmaking ingredients maintained in an elevated storage bin 75 (Fig. 1). Said storage bin 75 is connected by means of a flexible hose 76 to the upper portion, as at 77, of the hopper 47. Since, as will presently be explained, the hopper 47 is rotated with the frame 31 as a whole, a sufficient length of the hose 76 must be provided to accommodate such movement of the hopper, and for this purpose the hose is looped and is suspended at the loop 78 by a counterweighted cable 79 from a pulley 80. The counterweight 81 serves to hold the looped hose out of the way, but to permit an extension of the hose as the frame 31 is moved through 180 to its inverted position. No valve is necessary in the hose connection between the bin 75 and the hopper 47, since the normal operation of the machine insures a gravity feed of the mold-making materials in suflicient quantity to keep the hopper 47 filled at all times to the necessary extent. The upwardly bent loop 78 in the hose serves as a gooseneck to prevent flow of the mold making materials from the bin 75 into the hopper 47 except when the hopper is in its inverted position and the loop 78 has correspondingly been straightened out or extended downwardly.

The mechanism for effecting rotation of the invertible frame 31 includes a reversible motor 85 (Fig. 1) mounted on the lower platform 23 and connected'by means of a belt 86 through a stepped pulley 87 (Fig. 2) "and through a speed reducing mechanism 88 to a pinion 89. The pinion 89 serves to drive a chain 90 which is at all times trained around a pair of pinions, one of which is the lower pinion 91 that is mounted from the base of the stationary frame 21, by means of a floating support indicated generally by the reference numeral 92. Said support 92 includes a platform 93 apertured at its four corners for mounting upon four vertical studs 94. Springs 95 are mounted on each of said studs 94 and are held under compression thereon between the upper headed ends 96 and the platform 93. The pinion 91 is pivotally mounted on the platform 93 by means of a pair of links 97 and 98 which are pivoted together as at 99.

The other pinion of the pair around which the chain 90 is constantly trained may be either a pinion 100 supported from the cross framework 45 on the invertible frame 31, or a pinion 101 supported from the cross framework 50. In the normal, upright position shown in Figure 2, the pinion 100 is in engagement with the driving chain 90, while in the inverted position of the frame 31, as shown diagrammatically in Figure 4, it is the pinion 101 that is in driven engagementwith the chain 90. In order to guide the chain 90 into alignment with the sprockets of the movable pinions, the pinion 101 is provided with a guide plate 102, and the pinion 100 is provided with a guiding finger 103. The pinions 100 and 101 are, of course, fixedly supported so as not to be rotatable about their own axes.

A chain spreading bar 105 is secured to the sub-frame 36 by means of a plate 106 and screws or bolts 107. Said spreader bar 105 carries at each end a rigidly supported enlargement 108, each provided with an arcuate groove 109 for sliding, guiding contact with the chain 90. The length of the spreader bar 105 is such that, in conjunction with the spacing of the pinions that are in engagement with the chain at any time, it serves to hold the chain reasonably taut. Any slack in the ehain is taken up by the resiliently urged, floating pinion 91. It is thus possible to use an endless chain 90 for driving purposes.

The movement of the invertible frame 31 from its upright position shown in Figure 2 is illustrated diagrammatically by Figures 3 and 4. In Figure 3, as in Figure 2, the frame 31 is in its normal, upright position, although the hopper 47 is in its lowered position, cooperating with the die 56. From its normal position, as in Figure 3, the frame 31 is moved in a counterclockwise direction, as indicated by the arrow, through 180 until it reaches the position illustrated in Figure 4. In that position, the die 56 is at the upper position of its movement, while thehopper 47 is beneath the die but still in operative relation therewith. In the next movement of the frame 31, the frame is rotated in a clockwise direction, as indicated by'the arrow in Figure 4, back through 180 until it reaches its normal, upright position again.

The oven 30, which has previously been referred to only in passing, comprises a semi-cylindrical enclosure 110 that is open at the bottom and that has inturned flanged runners 111 on each side of the opening 112 (Fig. 2). The runners 111 are supported for sliding movement on suitable tracks. One set of tracks 113 is mounted upon the lower ends of the guide posts 41 (Figs. 1 and 2) and supports the oven 30 when in its advanced position, shown in dotted lines in Figure 1. When in that position, the oven 30 overlies the die 56 to heat the shell mold that has been formed on said die, as will be more fully explained hereinafter. In its rearward, or full line position as shown in Figure 1, the oven 30 is supported upon tracks (not shown) either secured to or supported from the horizontal track portions 27. The oven is provided with a plurality of heating elements 115 that extend the full length of the oven between the partial end closures 116 thereof. The heating elements 115 are arranged in an arc conforming with the segmental cylindrical shape of the enclosing casing 110, the inside of which is preferably heat reflective so as to concentrate the heat upon the upper surface of the die 56. Any radiant heating elements may be employed, but so-called Calrod elements have been found eminently satisfactory.

A hydraulic cylinder 120, supported on angle brackets 121 extending between the horizontal portions 27 of the frame 26, serves to move the oven 30 between its advanced and retracted positions. For this purpose, the piston (not shown) operating within the casing of the pneumatic cylinder is pivotally connected, as at 122, to the rear end of the oven 30 by means of a connecting rod 123.

Since it is necessary that the tracks 113 carried by the invertible frame 31 be accurately aligned for receiving the oven 30 when moved into its advanced position, means are provided for insuring such accurate alignment. These means, as best shown in Figures 1 and 5, include a support member 125 rigidly mounted from the uprights 21b at a point below but adjacent to the supporting platform 50 when at its lowest point of movement, namely, when the frame 31 is in its normal, upright position. A pair of spaced, vertically extending plates 126 and 127 are secured to the upper surface of the support 125. Said platform 50 has an extension 128 provided with an integral downturned end 129. The end 129 is adapted to move in between the plates 126 and 127 as the frame 31 swings into its normal, upright position. The plate-s 126 and 127 and the downturned end 129 are all provided with openings, which when the frame 31 is in its normal, upright position, are properly aligned, as indicated in Figure 5 by the dotted lines 130. When alignment occurs, mechanism is provided for locking the frame 31 in that position. Such mechanism includes a pneumatic cylinder 131, and piston rod 132. actuated thereby,.

diameter to fit snugly: within the aligned apertures. 130. The piston rod 132 has an actuating bar 135 attached thereto, as at 13.6, for movement therewith. Said actuator member 135'has a horizontally extending portion 137 on which. are.- mounted. spring biased contact members 138 and 139. Said contact members 138' and 139 are? each angle-shaped and pivotally mounted adjacent the vertex of the angle, as at 140 and 141, respectively; Stop. pins 142 and 143 prevent rotation of said angle members 138 and; 139 under the action of their respective springs. 144 and 145 so as to maintain one of the arms of said angle members in normally upright position. Switches and 151 are mounted above the actuator bar 135,. as by means of a bracket plate 146 from the horizontal frame members 27. The pneumatic cylinder 131 is also mounted from said member 146, asbymeans of angle. brackets 152'. Each of the. switch boxes 150 and 151 has a dependent finger 153 and 154, respectively, which extend into the path of the upper ends of the angle members 138 and 139 to be actuated thereby in the movement of the actuator bar 135. The purpose and mode of operation of the switches will be more fully explained in connection with the wiring diagram and the description of the operation of the entire machine.

The die 56 comprises a rectangularly shaped body portion (Figs. 10, 11 and 12) having a plane upper working face 161, from the edges of which extend upstanding wall members 162 that are secured to said body portion by means of screws 163 or the like. The walls 162 are preferably all of the same height, but at least the upper edges 164 of two opposite side walls lie in the same plane for a reason that will be later made apparent. Upon the working face 161 of the die are mounted the various part-s and elements that function to form the corresponding but reverse parts and elements of the shell molds. The parts and the elements on the working surface 161 will be described with reference to their functions in the formation of the mold for which my machine is designed. The raised portions on the working face 161 include a pouring basin 165 extending from one wall 162 and midway between the adjacent walls; a down gate 166 extending along a median line between said adjacent walls and toward the opposite wall but short thereof; runners 167 extending off to one side (the left side of view Fig. 9) from the down gate 166; gates 168 extending from said runners near the ends thereof; and patterns 169 and 170 connected by said gates to said runners. The patterns 169 and 170 may be composed of separate elements, referred to as prints, and indicated by reference numerals 172 and 173. Similar prints. 172a and 173a are shown on the other side of the down gate 166, but not connected thereto by runners. This is because the die 56 makes only a single mold half, and two identical mold halves are later placed face to face to make a complete mold. Consequently, since the working face 161 is divided symmetrically about the median line passing through the down gate 166, it is not necessary to provide runners on more than the one side of the down gate inasmuch as the runners in one half mold. serve as runners for the mold cavities in the other half mold when the half molds are in mated, face-to-face relationship.

Other raised portions on the working face 161 include raised bars 180, one on either side of the surface 161 and. extending parallel to the down gate 166, and a third bar 181 extending at right angles to the first two bars and across the blind end of the down gate 166, but out of contact therewith and. also with other bars 180. The bars -and 181 are of the same height, but of a lesser height than the top edges 164 of the side walls 162 while of slightly greater height than any of the other raised portions on the working face 161 of the die. The purand a comically pointed lockemgbolt. 133. having. a cylindricalportion of the; proper:

be more fully explained the raised portions, including the inner surfaces of the walls 162 are provided with a taper or draft, to facilitate the stripping of the mold from the pattern plate.

In order to avoid unnecessary repetition, the same-- reference numerals will be used in describing the mold, indicated generally by the letter M, produced from the die. or pattern plate, as has been used in describing the corresponding forming parts of the die, or pattern. plate.

The mold M is illustrated. in Figure 13 and constitutes merely the reverse of the surface contours of the pattern plate shown in Figure 9. Of course, since Figure 13 is a top plan view of the mold face that was molded in contact with the die face 161, the showing in. Figure: 13 is a mirror image; of the showing in Figure 9, as well as being a reverse, of the surface contours.

Returning to the. description of the die, itself, as shown in Figure l, the die 56 is adapted to be heated by electrical heating units indicated by the reference numerals 190. The heating units 190. may take the form of cartridges that are arranged to give a plurality of heating Zones in the body of the die, each of which is separately controlled by means of a thermostat through a dial 191 mounted on a wall of the die.

A pneumatic cylinder 192, suitably suspended from straps 193 below the die 56, is provided for the purpose of operating the knock-out pins previously referred to. Sincev the general construction and mode of operation of the mechanism for operating the knock-out pins through the medium of the pneumatic cylinder 192 are well known, no further description is deemed necessary.

Prior to starting up the machine various preliminary operations are carried out.

The sand-resin mix is prepared and stored in the overheadbin 75'. In general, a dry, pulverulent mixture of sand and resin in the proportion of 1 00 parts of sand and from 3 to 10' parts. by weight of resin has been found to be satisfactory.

The die 56 is prepared with the desired patterns mounted on its working face 161, and the die and pattern assembly then inserted in place in the machine, mounted upon the platform 50. After being so mounted, the die is heated by energizing the heating units and the dials 191 are adjusted to raise the die to the proper temperature.

A parting agent is next applied to the hot working face 161 and to the surfaces of the patterns and associated raised portions secured to said working face. Silicones are frequently used as the parting agent and may be sprayed on. A sufficient amount of the separating agent is applied to insure easy release of the mold.

The other operations in the making of sand-resin shell molds will be described in connection with the description of the wiring circuit.

In Figure 16, which is the circuit diagram, reference numeral 200 designates a main switch which may be closed to energize the control circuits. Reference numeral 2'01 designates a switch arm of an automaticrnanual selector switch which may be thrown to engage a contact 202 for automatic operation or thrown to engage a contact 203 for manual operation.

For automatic operation, it is necessary to first push down a start button 204 to energize the coil 205 of a relay 206. Contact 207 of the relay 206, which is a holding contact, bridges the start button 204 to maintain relay 206 energized. The lower contact 208 of the relay 206 is also closed, connecting line 209 to the switch arm 201 of the automatic-manual switch. A comparatively low A. C. control voltage is applied to the is. to, provide pressure on the back surfacesof the-- line 209 with respect to ground through a step-down transformer 210 having a primary 211 energized when the main switch 200 is closed and having a secondary 212, one terminal of the secondary 212 being connected to ground and the other terminal being connected to the automatic manual switch arm 201.

To start the automatic operation, the start button 213 is pushed down to energize an air valve control solenoid 214 which admits air to the cylinder 46 (Fig. 2) and causes the hopper 47 to be lowered to the position shown in Figure 3. When the hopper 47 reaches the limit of its downward travel, an actuator 215 (Fig. 2) engages and closes a micro-switch 216. At this point in the operation, the hopper 47 and die 56 are in the position shown in Figure 3,with the end flange 55 about the open mouth of the hopper in cooperative relation with the side walls 162 of the die to enclose the upper working face 161 thereof. The sand-resin mixture within the hopper 47 is rerained therein by the closed gate valve 60. Above the valve 60, the hopper will be substantially full of the sandresin mixture owing to the fact that the hose 76 will then be sufficiently straightened out to let the mixture flow by gravity from the main supply bin 75 into the hopper. When the micro-switch 216 is closed, an air valve control solenoid 217 is energized to cause air to be admitted to the cylinder 62 (Fig. 6) and to move the gate valve 60 outwardly to its open position. As the valve 60 opens, the sand-resin mixture above the valve starts to fall down onto the heated working face 161 of the die 56. Since the dimensions are such that there is a fall of at least a foot, the sand-resin mixture tends to pack rather uniformly as it builds up on the working face 161. The temperature of the working face and of the patterns and raised portions on said face should be between 400 and 500 F. at the time that the valve 60 opens so that upon coming into contact with said heated surfaces, the sand-resin mix will be heated to a temperature at which the resin will start to fuse.

At the limit of the outward travel of the gate valve 60, a pin 218 (Fig. 6) which is fixed thereto, engages and closes a micro-switch 219. In closing, switch 219 energizes a time delay relay coil 220. After a predetermined interval of time, during which the sand-resin mix in contact with the die 56 forms a fused layer of optimum thickness, relay contact 220a is opened and contact 22% is closed. Contact 220b completes a circuit to an air valve control solenoid 2200 which admits air to the cylinder 131 (Fig. and retracts the locking pin 133.

It may require from 3 to 20 seconds for a partially fused sand-resin layer of between Va and A inch in thickness to build up on the die 56 in contact with the surface 161 and the raised portions thereon. This fused layer, which is identified generally by the reference numeral 300 (Figs. 10 and 11), is relatively coherent and is also sufficiently adherent to the die and pattern surfaces with which it is in contact to adhere thereto when the die is subsequently inverted to remove whatever loose sand-resin mix will fall away by gravity.

During the retracting movement of the locking pin 133, the terminal cam end 137a of the actuator member 135 (Fig. 5) closes a safety switch 221 which is in the circuit of the roll-over motor 85 as will be described in detail hereinafter. When the locking pin 133 is fully retracted, the actuator 139 engages the finger 154 of the micro-switch 151 and closes the switch.

The micro-switch 151 is in series with a lower contact 222 of a relay 223 having a coil 224 in parallel with the coil 205 of the relay 206 and energized when the start button 204 is pushed down. At this point, it should be first noted that a plurality of terminals 225- 230, illustrated in Figure 16, are connected to (not shown) for the roll-over motor 85. When terminals 225 and 226 are connected together, the motor 85 is energized so as to rotate the frame 31 in what a controller.

will be termed a forward direction (clockwise, in- Figures 2-4). When terminals 227 and 228 are connected 'to' gether, the motor is energized so as to rotate the frame 31 in a reverse direction (counterclockwise, Figures 2-4). When terminals 229 and 230 are connected together, energization of the motor 85 is possible, but if they are not connected together, it is not possible to energize the motor 85.

With the micro-switch 151 closed by movement of the locking pin 133 to the limit of its outward travel and with contact 222 of relay 223 closed, the terminals 227 and 228 are connected together and the motor 85 rotates the frame 31 in a reverse direction (counterclockwise as shown in Figs. 2, 3 and 4).

As the frame 31 moves to its inverted position (Fig. 4) with the hopper 47 and die 56 still'in their cooperative engagement and with the valve 60 still in open position, the loose, pulver-ulent sand-resin mix on the die falls back into the hopper, leaving the partially fused layer 300 in adherent contact with said die face 161 and with the raised surface portions mounted thereon. When the frame 31 reaches the limit of its travel (counterclockwise direction), an actuator 231 (Fig. 2) affixed thereto will engage and momentarily open a switch 232 to open the stop circuit of the motor 85 between terminals 229 and 230 and actuator 231 will then close a micro-switch 233.

Micro-switch 233 in closing energizes an air valve control solenoid 234 which admit air to the cylinder 62 (Fig. 6) to move the gate valve 60 inwardly toward its closed position. By the time the valve is fully closed all of the loose sand-resin mix has fallen from the die back into the hopper, where it is retained until the next cycle of operation. When the gate valve 60 reaches the limit of its inward closing travel, an actuator 235 fixed to the gate valve 60 will close a micro-switch 236 attached to the frame 63.

Micro-switch 236 is in series with a contact 237 of the relay 223 and connects terminals 225 and 226 together to energize the roll-over motor 85 and rotate the frame 31 in a forward direction (clockwise, Figs. 2-4).

When the frame 31 reaches the limit of its forward travel, an actuator 238, (Fig. 1) attached to the lower platform 50 of the frame 31 closes a micro-switch 239 (Fig. 2) while momentarily opening a switch 240 (Fig. 2) in series between the terminals 229 and 230 to deenergize the roll-over motor 85.

Micro-switch 239 energizes an air valve control solenoid 241 which admits air to the cylinder 46 (Fig. 2) and causes the hopper 47 to be elevated to the position shown in Figures 1 and 2.

At the end of the upward travel of the hopper, an actuator 242 attached thereto engages and closes a microswitch 243 (Fig. 2).

Micro-switch 243 energizes an air valve control soleno d 244 to admit air to the cylinder 131 (Fig. 5) and cause the pin 133 to move inwardly into locking engagement with the member 129 on the frame 31. At the limit of the inward travel of the locking pin 133, the actuator 138 engages the actuating pin 153 of microswitch 150 to close the switch.

Micro-switch 150 is in circuit with an air valve control solenoid 245 which admits air to the cylinder (Fig. 1) to move the oven 30 inwardly toward a position over the die, as indicated in dotted lines.

The oven 30 carries at one end a scraper bar 301 (Figs. 2, 11 and 12), which is pivotally mounted at 302 between the side walls of the oven so that its lower edge 303 depends below the lower edges 111 of the side walls of the oven casing 110. An arcuate-shaped spring 304 supported from a cross bar 305 resists swinging movement of the bar 301 in one direction but permits movement of the bar in the other direction. As the oven 30 moves inwardly toward a position on the tracks 113 (Fig. 1) and over the die 56, the scraper bar 301 is held by the spring 304 in pressure contact with the upper edges 164 of two opposed walls 162 of the die to scrape ofi any SfiILdeI'tiSln mix lying. above. the plane 3% represented. by said upper edgesand indicated by a dotted line in Figs. 10. and: 1.1. This. operation provides coplanar surfaces 397 on the back side of the. sand-resin layer 3% and it is these coplanar surfaces that provide the pressure point, or areas 308 (Fig. 14) in the finished shell mold SM.

When the. oven 3 B. reaches the limit of its inward. travel, an actuator 246 attached thereto closes a micro.- switch 247. Micro-switch 247 is in circuit with a coil 248. of a time delay relay 249. If desired, micro-switch 247' might also, control electrical heating elements 11.5 of the oven 30.. Regardless. of how they are energized, the heating elements 115 of the oven are energized. by the time the oven has moved into the dotted line position shown in Figure 1. There, the oven establishes a temperature of from 675 to 725 F. adjacent the surface of the sand-resin layer d. After a short length of. time, say, from. A to 2 minutes, curing of the layer 300- is completed.

The time delay relay 249 then actuates a contact 250 to: open position and a contact 251 to closed position. Contact 251 is in circuit with an air valve control solenoid 252 which admits air to the cylinder 120 and retracts the oven 30. As the oven moves off the tracks 113-, the scraper bar 301 is pulled along with the oven and drags over the top edges of the walls 162 without doing any work.

At the end of the outward travel of the oven 30, an actuator 253 attached thereto engages and closes a microswitch 254. Micro-switch 254 is in circuit with an air 1 valve control solenoid 255 which admits air to the cylinder 192 (Fig. 2) and causes the knock-out pins 187 to move upwardly. The finished shell mold half SM is manually stripped from the die at this point.

At the end of the upper travel of the pins 187, an actuator 256 movable therewith closes a micro-switch 257;

Micro-switch 257 is in circuit with a solenoid 258' which admits air, to the cylinder 192' and pulls the knockout pins 187 downwardly. This is the end of the cycle of automatic operation. In order to start the cycle anew, it is necessary to again press down the automatic start button 213.

To deenergize the automatic control circuits, a stop button 259 may be pressed down to open the circuit to the relay coils 2G5 and 224 and thus deenergize' the relays.

For manual operation, the switch arm 291 may be turned to engage the contact 203 and apply voltage to a line 260 which may be connected by means of push buttons to the various air valve control solenoids. In particular, a button 261 may be pushed down to energize the air valve control solenoid 214 to admit air to the cylinder 46 (Figs. 1 and 2) and lower the hopper 47. After the hopper is lowered, a button 262 may be pressed down to energize the air valve control solenoid 217 to cause air to be admitted to the cylinder 62 and move gate valve 69 outwardly to its open position. The sandresin mix then flows down onto the die 56 and after it has fused into a layer of optimum thickness, 21 button 263 may be pressed down to energize the air valve control solenoid 220C to cause the locking pin 133 to retract. When the locking pin 133 is fully retracted, a button 264 may be pressed down to connect the terminals 227 and 228 to energize the roll-over motor and rotate the frame 31 in a reverse direction (counterclockwise, Figs. 2-4).

The button 265 may then be pushed down to energize the air valve control solenoid 234 and admit air to cylinder 62 in a direction such as to move the gate valve inwardly to its closed position. A push button 266 may then be pushed downwardly to connect the terminals 225' and 226 to energize the roll-over motor and rotate the frame 31 in a forward direction (clockwise, Figs. 2 4). When the frame 31' reaches. the. limit: of its forward .traveLa button 267 may be pushed down to energize the. air valve control solenoid 241 to admit air to thefcylinder 46 in a direction such; as to cause the hopper 47 to. raise. After the hopper 4.7 is fully raised, a button 263: may bev pushed down to energize the air valve control solenoid 244-. and admit air to. the cylinder 131 in a direction such as to cause the pin 133 to be pushed into locking engagement with the member 129 on the frame 31.

A button 269 may thenv be pushed down to energize the: air valve control solenoid 245 to admit air to the cylinder 120 in a direction such as tomove the oven 3t inwardly into its. position over the mold as indicated in dotted lines (Fig. 1). If desired, the electrical heating elements in the oven 39 might be simultaneously energized. After heat has been applied to the mold for an optimum length of time, a button 270 may be pressed downwardly to energize the air valve control solenoid 252 and admit air to the cylinder in a direction such as to retract the oven 30.

A button 271 may then be pushed downwardly to energize the solenoid. 255 and admit air to the cylinder 192 a direction such as to cause the knock-out pins 187 to move upwardly. After the mold is ejected, a button 272 may be pressed: down to energize the air valve control solenoid 258and admit air to the cylinder 192 in a direction such as to pull the pins 187 downwardly. This is the endof the manual cycle.

It should be noted that the roll-over motor 85 is automatically deenergized at the end of the reverse rotation of the. frame 31 by the actuator 231 engaging and opening the micro-switch 232. in series between the terminals 229 and 23.0, in manual as well as automatic operation. offthe. machine. Likewise, the motor 85 is automati'call'y deenergized at the end of the forward travel of the frame 31 through opening of the switch 240.

If, at any time, whether in manual or automatic operation, it is desired to stop the roll-over motor, this may be accomplished by pushing down a button 273 to open the circuit between the terminals 229 and 230. As a safety measure, energization of the roll-over motor 85 is also prevented when the locking pin 133 is not fully retracted, when the oven 30 is moved inwardly or when the load on the roll-over motor 85 exceeds a predetermined value. For this purpose, a switch 274 (Figs. 15 and 1.6)' is arranged so as to be closed only when the oven 30 isfully retracted and is connected in series between theterminals 229 and 230. The switch 221 which,

the terminals 229 and 23d, and a switch 274a which is 2 arranged, in a manner not illustrated, to open when the mounting for'the motor 85' is displaced a predetermined amount in response to undue load is also connected between the terminals 22? and 230.

Asshown in Figure 14, a plurality of shell mold halves SM, made as described, are assembled for pouring with relatively thin'shell mold walls would flex, bulge or even rupture under the forces. exerted. against them.

I claim as my invention: 1. A mold making machine, comprising an open-ended hopper for holding a supply of mold-making materials, a die having raised patterns on an open face thereof, an invertible frame supporting said hopper and die in aligned parallelopposedrelationship with the open end of said hopdie when said frame is in normal position, means within said die for heating the same to convert some of said mold-making ingredients into .a coherent layer covering said patterns and adhering thereto, and means movable laterally with respect to said frame for scraping the top of said layer to form a plurality of co-planar surfaces thereon.

2. A mold making machine, comprising an openended hopper for holding a supply of mold-making material, a die having raised patterns on an open face thereof, an invertible frame supporting said hopper and die in aligned parallel opposed relationship with the open end of said hopper toward the open face of said die, means for relatively moving said hopper and die toward each other, gate means within said hopper for releasing said mold-making materials from said hopper onto the open face of said die when said frame is in normal position, means within said die for heating the same to convert some of said mold-making ingredients into a coherent layer covering said patterns and adhering thereto, scraping means carried on a movable oven for forming a plurality of co-planar surfaces on the top of said layer, and means for moving said oven first to effect said scraping operation and then to position said oven over said die to bake said layer into a shell mold.

3. A mold making machine, comprising an open-ended hopper for holding a supply of mold-making materials, a tray-like die having raised patterns on an open face thereof and having opposite walls providing top edges at a level above said raised patterns, an invertible frame supporting said hopper and die in aligned parallel opposed relationship with the open end of said hopper toward the open face of said die, means for relatively moving said hopper and die toward each other, gate means within said hopper for releasing said mold-making materials from said hopper onto the open face of said die when said frame is in normal position, means within said die for heating the same to convert some of said mold-making ingredients into a coherent layer covering said patterns and adhering thereto, means for inverting said frame to return an excess of mold-making materials from said die back into said hopper, and scraping means movable over said die in contact with said top edges after the operation of said inverting means to form a plurality of co-planar surfaces on the top of said layer flush with said top edges.

4. A mold making machine, comprising an open-ended hopper for holding a supply of mold-making materials, a die having raised patterns on an open face thereof, an invertible frame supporting said hopper and die in aligned parallel opposed relationship with the open end of said hopper toward the open face of said die, means for relatively moving said hopper and die toward each other, gate means within said hopper for releasing said mold-making materials from said hopper onto the open face of said die when said frame is in normal position, means for inverting said frame to return an excess of mold-making materials from said die back into said hopper, said means including a chain, pinions at opposite points on said frame for selective engagement with said chain and a reversible motor for driving said chain.

5. A mold making machine, comprising an open-ended hopper for holding a supply of mold-making materials, an elevated stationary source of supply of said materials, a flexible condui for feeding said materials automatically by gravity into said hopper, a die having raised patterns on an open face thereof, an invertible frame supporting said hopper and die in aligned parallel opposed relationship with the open end of said hopper toward the open face of said die, means for relatively moving said hopper and, die toward each other, gate means within said hopper for releasing said mold-making materials from said hopper onto the open face of said die when said frame is in normal position, and means for inverting said frame to return an excess of mold-making materials from said die back into said hopper.

. 6. A.moldmakingmachine comprising an open-ended hopper for holdinga supply of mold-making materials, anelevated stationary source of supply of said materials, a flexible conduit for feeding said materials automatically by gravity into said hopper, a die having raised patterns on an open face thereof, an invertible frame supporting said hopper and die in aligned parallel opposed relationship with the open end of said hopper toward the open face of said die, means for relatively moving said hopper and die toward each other, gate means within said hopper for releasing said mold-making materials from said hopper onto the open face of said die when said frame is in normal position, and means for inverting said frame to return an excess of mold-molding materials from said die back into said hopper, said means including a chain, pinions at opposite points on said'frame for selective engagement with said chain and a reversible motor for driving said chain.

7. A mold making machine, comprising an open-ended hopper for holding a supplyof mold-making materials, an elevated stationary source of supply of said materials, -a flexible conduit for feeding said materials automatically by gravity into said hopper, a tray-like die having raised patterns on an open face thereof and having opposite walls providing top edges ata level above said raised patterns, an invertible frame supporting said hopper and die in aligned parallel opposed relationship with the open end of said hopper toward the open face of said die, means for relatively moving said hopper and die toward each other, gate means within said hopper for releasing said mold-making materials from said hopper onto the open face of said die when said frame is in normal position, means within said die for heating the same to convert some of said mold making materials into a coherent layer covering said patterns and adhering thereto, means for inverting said frame to return an excess of mold-making materials from said die back into said hopper, and scraping means movable over said die in contact with said top edges to form a plurality of coplanar surfaces on the top of said layer flush with said top edges, said means for inverting said frame including a chain, pinions at opposite points on said frame for selective engagement with said chain and a reversible motor for driving said chain.

8. A mold making machine, comprising an open-ended hopper for holding a supply of mold-making materials, an elevated stationary source of supply of said materials, a flexible conduit for feeding said materials automatically by gravity into said hopper, a die having raised patterns on an open face thereof, an invertibleframe supporting said hopper and die in aligned parallel opposed relationship with the open end of said hopper toward the open face of said die, means for relatively moving said hopper and die toward each other, gate means within said hopper for releasing said mold-making materials from said hopper onto the open face of said die when said frame is in normal position, means within said die for heating the same to convert some of said mold making materials into a coherent layer covering said patterns and adhering thereto, means for inverting said frame to return an excess of mold-making materials from said die back into said hopper, and means for scraping the top of said layer to form a plurality of coplanar surfaces thereon, said means for inverting said frame including a chain, pinions at opposite points on said frame for selective engagement with said chain and a reversible motor for driving said chain.

9. A mold making machine, comprising an openended hopper for holding a supply of mold-making materials, an elevated stationary source of supply of said materials, a flexible conduit for feeding said materials automatically by gravity into said hopper, a die having raised patterns on an open face thereof, an invertible frame supporting said hopper and die in aligned parallel opposed relationship with the open end of said hopper toward the open face of said die, means for relreversible motor for 1-5 atively moving said hopper and die toward each other, gate means within said hopper for releasing said moldmaking materials fromsaid hopper onto the open face of said die when said frame is in normal position with said hopper disposed above said die, means within said die for heating the same to convert some of said moldmaking ingredients into a coherent layer covering said patterns and adhering thereto, scraping means carried on a movable oven for forming a plurality of co-planar surfaces on the top of said layer and means for moving said oven first to eifect said scraping operation and then to position said oven over said die to bake said layer into a shell mold, and: means for inverting said frame pinions at oppositepoint's on said frame for selective engagement with said chain and a driving said chain.

10. In a sand-resin shell mold making machine, an open-ended hopper for holding a supply of a pulverulent mixture of sand and resin, a tray-like die having opposite walls of the same height and raised patterns therebetween of lesser height, an invertible frame supporting said hopper and die in aligned parallel opposed of said sand-resin mixture into a coherent layer extendsaid hopper and then returning said frame to normal upright position, and scraping means thereafter movable into contact with the upper edges of said opposite Walls to scrape loose mixture off of said layer to the level of said wall edges.

11. In a sand-resin shell mold making machine, an open-ended hopper for holding a supply of a pulverulent mixture of sand and resin, 2. tray-like die having opposite walls of the same height and raised patterns therebetween of lesser height, an invertible frame supporting said hopper and die in aligned parallel opposed relationship whereby said sand-resin mixture may be dumped from said hopper onto said die when said frame is in normal upright position with said hopper disposed above said die, means within said die for heating the same to fuse some of said sand-resin mixture into a coherent layer extending over said patterns and adhering thereto, means for inverting said frame from normal upright position to dump an contact with the upper edges of said opposite walls to scrape loose mixture off of said layer to the level of said wall edges, and an oven movable over said die to complete the curing of the resin in said layer to form a shell mold therefrom.

12. In a sand-resin shell mold making machine, an open-ended hopper for holding a supply of a pulverulent mixture of sand and resin, a tray-like die having opposite Walls of the same height and raised patterns therebetween of lesser height, an invertible frame supporting said hopper and die in aligned parallel opposed relationship whereby said sand-resin mixture may be dumped from said hopper onto said die when said frame is in normal upright position with said hopper disposed above said die, means within said die for heating same to fuse some of said sand-resin mixture into a coherent layer extending over said patterns and adhering thereto, means for inverting said frame from normal upright position to dump an excess of said mixture from said die back into said hopper and then returning said frame to normal upright position, scraping means thereafter movl 5 able in contact with the upper edges of said opposite walls to scrape loose mixture off of said layer to the level of said wall edges, and an electrical circuit including automatic controls for operating said die heating means, inverting means and scraping means in proper sequence.

13. In a sand-resin shell mold making machine, an open-ended hopper for holding a supply of a pulverulent mixture of sand and resin, at tray-like die having opposite walls of the same height and raised'patterns ther'ebetween of lesser height, an invertible frame supporting said hopper and die in aligned parallel opposed relationship whereby said sand-resin mixture may be dumped from said hopper onto said die when said frame is in normal upright position with said hopper disposed above said die, means within said die for heating the same to fuse some of said sand-resin mixture into a coherent layer extending over said patterns and adhering thereto, means for inverting said frame from normal upright position to dump an excess of said mixture from said die back into said hopper and then returning said frame to normal upright position, a gate within said hopper controlling the dumping of said mixture from said hopper onto said die, scraping means thereafter movable in contact with the upper edges of said opposite walls to scrape loose mixture off of said layer to the level of said wall edges, an oven movable over said die to complete the curing of the resin in said layer to form a shell mold therefrom, and an electrical circuit including automatic controls for operating said die heating means, inverting means, said gate, the movement of said oven and scraping means in proper sequence.

14. In a sand-resin shell mold making machine, an open-ended hopper for holding a supply of a pulverulent mixture of sand and resin, a tray-like die having opposite walls of the same height and raised patterns therebetween of lesser height, an invertible frame supporting said hopper and die in aligned parallel opposed relationship whereby said sand-resin mixture may be dumped from said hopper onto said die when said frame is in normal upright position with said hopper disposed above said die, means Within said die for heating the same to fuse some of said sand-resin mixture into a coherent layer extending over said patterns and adhering thereto, means for inverting said frame from normal upright position to dump an excess of said mixture from said die back into said hopper and then returning said frame to normal upright position, scraping means thereafter movable in contact with the upper edges of said opposite walls to scrape loose mixture ofiF'of said layer to the level of said wall edges, and driving means including a chain, pinions carried by said frame at opposite points thereon for selective engagement with said chain as the same is driven, and a reversible motor for driving said chain.

15. In a sand-resin shell mold making machine, a traylike die having opposite walls with their top edges in the same plane, raised patterns between said Walls with their raised surfaces lying below said plane and means for heating said die to fuse the resin in sand-resin mix- 'ture placed on said die and thereby form a coherent sand resin layer overlying said patterns and adhering thereto.

16. In a sand-resin shell' mold making machine, a traylike die having opposite walls with; their top edges in the same plane, raised patterns between said walls with their raised surfaces lying below said plane and means for heating said die to fuse the resin in sand-resin mixture placed on said die and thereby form a coherent sand-resin layer overlying said patterns and adhering thereto, an oven movable over said die having a scraper bar pivotally mounted thereon, and means for moving said oven into place over said die and simultaneously causing said scraping bar to scrape off an excess of sandresin mixture above said plane of said top edges.

17. In a shell mold making machine, an oven of arched shape and open at the bottom, and a scraper bar at' its ends from the side walls of said oven said open bottom and project supported to extend transversely of slightly therebelow.

18. In a shell mold making machine, an oven of arched shape and open at the bottom, a scraper bar supported at its ends from the side walls of said oven to extend transversely of said open bottom and project slightly therebelow, means supporting said bar for pivotal movement, and resilient means opposing such pivotal movement in one direction.

19. A sand-resin shell mold making machine, comprising a supporting stand, an invertable frame including parallel guide bars, means pivotally supporting said frame from said stand, a mold forming die at one end of said frame, 28. hopper mounted on said guide bars for movement therealong into cooperation with said die, an elevated source of supply of a pulverulent sand-resin mix, a flexible hose from said source to said hopper for gravity feed thereto, a gate controlling the discharge of said sandresin mix from said hopper onto said die, means con trolling the operation of said gate, driving means including an endless chain, pinions carried at opposite points on said frame for selective engagement with said chain and a reversible electric motor for driving said chain to move said frame from normal upright position to inverted position and back again, and an electrically op- 18 erated circuit including controls for moving said hopper into cooperation with said die, for operating said gate to discharge sand-resin mix from said hopper onto said die, for inverting said frame to dump an excess of sandresin mix from said die back into said hopper and for returning said frame to normal upright position.

References Cited in the file of this patent UNITED STATES PATENTS 1,434,508 Shimon Nov. 7, 1922 1,910,354 Nicholls et al. May 23, 1933 2,654,925 Ensign et a1 Oct. 13, 1953 2,659,945 Valyi Nov. 24, 1953 2,669,758 Valyi Feb. 23, 1954 FOREIGN PATENTS 680,699 Great Britain Oct. 8, 1952 OTHER REFERENCES The Iron Age, April 19, 1951, pages 81-85. Fortune, July 1952, pages 104-107, 140 and 143. Am. Foundryman, Aug. 1952, pages 42-46. Foundry, Sept. 1952, pages 95-97 and 108-111. Steel, Oct. 6, 1952, pages 83 and 84.

Foundry, Nov. 1952, page 265. 

